Algal biodiesel production with engineered biochar as a heterogeneous solid acid catalyst

Area of Science:

• Biomass Conversion
• Catalysis
• Renewable Energy

Background:

• Microalgal oil is a sustainable feedstock for biodiesel production.
• Heterogeneous solid acid catalysts offer advantages over homogeneous catalysts in biodiesel synthesis.
• Biochar, a carbon-rich material from biomass pyrolysis, can be engineered for catalytic applications.

Purpose of the Study:

• To evaluate engineered biochar as a solid acid catalyst for transesterification of algal oil.
• To optimize reaction conditions for maximum biodiesel yield.
• To characterize the resulting algal biodiesel.

Main Methods:

• Biochar was produced from various biomass sources (sugarcane bagasse, coconut shell, corncob, peanut shell) and surface-modified.
• Peanut shell biochar pyrolyzed at 400°C with high sulfonic acid density was selected.
• Transesterification of algal oil was performed using the engineered biochar catalyst under varying conditions (catalyst loading, methanol:oil ratio, temperature, time).

Main Results:

• The optimal catalyst was peanut shell biochar (400°C pyrolysis, 0.837 mmol/g sulfonic acid density, 6.616 m²/g surface area).
• A maximum biodiesel yield of 94.91% was achieved using 5 wt% catalyst loading, a 20:1 methanol:oil ratio, at 65°C for 4 hours.
• Spectral analysis confirmed ester functional groups, and GC-MS identified palmitic and oleic acids in the biodiesel.

Conclusions:

• Engineered biochar, particularly from peanut shells, is an effective heterogeneous solid acid catalyst for algal oil transesterification.
• The optimized process yields high-purity biodiesel suitable for commercial applications.
• This technology presents a sustainable route for biofuel production from microalgae.